Electromagnetic relay



M y 7, 1929. G. A. E. LUNDELL 1,711,958

ELECTROMAGNETIC RELAY Original Filed March 21,- 1321 it; 47 zaa 205 105 V QQ Patented May 7, 1929.

UNITED STATES PATENT OFFICE.

GEORGE ALBEN E. LUNDELL, OF NEVJ YORK, N. Y.; JEANNETTE DOLORES LUNDELL EXECU'IRIX F SAID GEORGE ALBEN E. LUNDELL, DECEASED.

ELECTROMAGNETIC RELAY.

Application filed March 21, 1921, Serial No. 453,959. Renewed August 29, 1928.

This invention relates to electro-magnetic relays, and more particularly to elcctro-magnetic relays having a marginal adjustment.

Heretotore in relays ot the marginal type the passage through the relay coil of a relatively Weak current, known as a non-operatting current, although it does not actually operate the relay, has caused the contact pressure of certain of the contact springs to be reduced. Such reduction in the contact pressure reduces the reliability of the contact, and the proper operation of the circuit ot' which such cont-act forms a part, may seriouslybe interfered with thereby. Adjustments of such relays to meet predetermined operating or non-operating values of current have heretofore been obtained by changing the tension of the contact springs, and modifications ot the adjustment have been extremely difficult to obtain Without also varying the pressure at the contacts, made by such springs. The ratio ofthe non-operating current to the operating current in relays of the prior art has been 75% to 90%. Any increase in this ratio results in a reduction of the number of relays rejected on inspection tests for poor operation. It has been ditlicult in relays of the prior art to obtain greater ratio than about 80% Without serious effect on the reliability of the contact. Thus a great saving in inspection rejection costs can be made by improved methods of adjustment. In bending contact springs the tools generally employed for the purpose necessarily establish electrical connections between the different springs of the relay and when making such adjustment in an operating exchange, where the circuit of which the relay forms a part is taken out of active service, it has heretofore been necessary to remove fuses in order to permit a change in the. adjustment of such marginal relays.

According to one feature of the present iii-- vention, I provide an adjusting means for an elmire-magnetic relay by which the actuation of the circuit controlling springs at a prod termined current value may be etliciently obtained independent of the contact pressures or such springs. The adjustment may be varied at will to suit the current requirements of dillerent operating conditions, with a constant tension in the circuit controlling springs and substantially unchanged reliability of the contacts thereof.

According to another feature of the invention, the passage of the non-operating current, that is a predetermined value of current on which the circuit controlling springs are expected not to be actuated can take place with unimpaired contact pressure of the normally closed circuit controlling springs. The expense of an additional relay in local circuit of the marginal relay and the space taken by it is thus eliminated.

According to still another feature of the invention, the magnetic characteristics of the magnetic circuit of the relay can be varied at will in a convenient manner, the adjusting means being accessible. from the spring end of the relay, thus the saturation point can readily be varied at will.

Another feature relates to making the adjustment for actuation of the circuit controlling springs with a predetermined value of current flowing at a time when the relay remains connected in circuit with a source of current connected to its contact springs.

Still another feature relates to improving the ratio between the predetermined nonoperating value or current and the predetermined operating value, thus providing improved methods in inspection of such relays.

In the drawings:

Figure 1 shows a top view of the contact spring assembled;

Figure 2 shows a side view of the relay with the armatures in place;

Figure 3 shows an end view of the contact springs and armaturcs;

Figure 4c shows the connecting end of the contact springs with parts broken away;

Figure 5 shows an armature having large cross section area;

Figure 6 shows an end view of the armature of Figure 5;

Figure 7 shows an end view of the armature of small cross section area;

Figure 8 is a side view of the armatin'c of Figure '7 Figure 9 shows the connecting end of the springs oppositely situated to Figure t and with parts broken away;

Figure 10 shows details of the magnetic circuit ot' the relays and the supporting members for the contact springs;

Figure 11 shows an end view of the connected end of the relay; and

- Figure 12 shows the means for adjusting the relay to operate on varying values of current.

The coil 21 forins an energizingwinding upon a core 22 and is retained thereupon by the insulating spool heads 23, 24. The core 22, which may be of any suitable paramagnetic material is provided witha rearwardly extending portion 25 having the extensions 26, 27 which. by means of suitable threaded screw holes are adapted to be rigidly secured to a supporting plate (not shown). Two

arms 201, 202 are also provided for a purpose to be subsequently set forth.

Supported by the upper and lower extremities of the portion 25 by means of the spring plate 28 and lugs 33, is the armature 30. This armature 30 may be of any suitable shape and of any suitable paramagnetic material, and one part thereof extends to a side of the forwardlyextending polepiece' 36 of the core 22. Mounted upon the same extremities of the portion 25 are respectively the circuit controlling springs 114,115, 116, 314 and the terminal post 134 in the upper group, insulated from 'each other and from the core 22 by suitable insulating plat-es and bushings and circuit controlling springs105, 205, 203, 204 and the terminal post 109 in the other group, similarly insulated. It is understood that any suitable arrangement or combination of such circuit cont-rolling springs may be employed without departing from the spirit of the invention. The terminal posts 134, 109 are connectedto the coil 21, itbeing understood that additional posts may be pro- "ided in a manner well known in the art, should they be required by'the conditions in the circuit in which such relays may be used.

The circuit controllingsprings are provided with the usual contac't points to complete the circuit between them. Attached to the free end of the armature 30 are the insulating studs 44, 44. These studs 44, 44 serve to maintain the armature 30 at a distance from the pole-piece 36 because of tension in the circuit controlling springs 105, 115. Thus in the normal position there is an air gap between the armature 30 and the polepiece 36." The retroactive movement of the arn'iat-ure 30 is limited by the nut- 40 and the washer 38, mounted upon the stud37.' The stud 37 is rigidly secured. to the core extension 36. I

\Vhen the armature is attracted towards the pole-piece 36 the studs 44, 44 serve to open or close the associated circuit controlling springs ot the relay. In therelay of the present invention such movement of the 'armature 30 causes the contact between springs 115. 314 and 105, 205, and 203', 204 to be made and that between springs 115, 116 to be broken. y

Supported by the 201, 2,02, by neans of the spring plate 31, 31 isthe armature 32. This armature 32 may be'of any'suitable paramagnetic material and may be formed in any suitable shape with a cross section that is substantially less than that of armature 30, and one part thereof extends to one side of the forward extension 42 of the member The member 322 has a pair of shoes 302 of wedge shape and thus having a varying cross section area substantially less than that of the core 22 and the portion 36.

Mounted also upon the arms 201, 202 are the separating plates 49, 49 and the butter springs 43, 43. A port-ion of each of the butter springs 43, 43 rests upon the spool head 24 and said springs 43, 43 serve to limit the movement of the armature 32 away from the pole piece 42.

Attached to the armature 32 are the insu lating studs 46, 47, which extend to the springs 114, 305. These springs 114, 305 have a tcnsionan'd thus serve to maintain the armature 32 at a distance from the extending portion 42 of the core.

Thus it will be seen that the magnetic circuit of the relay consists of the actuating portion 22 in which there is set up a magnetic field of force. The return path for the magnetic lines of force consists of separate branches; one of relatively small cross section area consisting of the arms 201, 202, the armature 32, the pole-picce 42, member 322, shoes 302, 302; and the otherconsisting of the portion 25, the armature 30 and the polepiece 36. These return paths are in shuntwith each other. The saturation point of the return path of small cross section area is variable by means of the adjustment of nut 340, and the wedge shaped shoes 302, 302.

The energization of winding 21 with current of relatively high value sets up in the core 22 a magnetic field of strong intensity. The return path oft these magnetic lines of force consists of separate branches; one of relatively small cross section area consisting of the arms 201, 202, the armature 32, the pole-piece 42, 322, 302; and the other consisting of the portion 25, the armature 30 and the pole-piece 36. These return paths are in shunt with each other. The saturation point of the return path which includes the armature 32 is determined by the area of contact between the shoe 302 and the polepiece 36 and may be adjusted or varied at will by means of the not 340. In the present instance it is adjusted so that the cross section area in contact and therefore available for passage of lines of force is suflicicntly small so the saturating point of the associated return magnetic is exceeded. On account of the relatively larger cross section area of the return path which includes armature-30, a strong attractive force is set up causing the movement of armature 30. The studs 44, are thereby pressed against springs 105, 115 and overcome the tension in these springs 'and causing the circuit controlling contacts to be actuated. In the present disclosure spring 115 breakscontact with. spring 116 upon such actuation; and spring 115 makes contact with spring 114; also spring 105 makes with 205; and 203 with 204, spring 203 being mechanically linked with spring 105 by an insulated stud in a well known manner. The flexible springs 305, 11% interconnect the two armatures 30 and 32 and the armature 32 may or may not be in its actuated position.

lVhen the current V the winding of the relay is of relatively low intensity the magnetizing force is not suflicient to bring the magnetic flux above the saturation point of the return path comprising armature 32.

The armature 30 meets the opposition of the tensioned springs 105, 115 as well as the opposing attractive force of the armature 32 transmitted through the springs 114, 305. It will be seen that the contact between springs 115, 116 is substantially unchanged by the pressure of stud 4% against sprin 115 and the circuit through the contacts or said springs 115, 116 be safely relied upon.

Referring to Figure 12, the stud 3? extends through the polepiece 3G. Secured to one face of the pole-piece 30 is a strip 336 made of non-magnetic material and of substantial stiffness. Secured to the free end of said strip 336 is a short flexible strip 3&2, to which is supported the pole-piece 42, 322. The rear end of 322 comprises a straight portion 301 and a pair of bent shoes 302, 302. Said shoes 302 are wedge-shaped so that the cross section area thereof decreases as the extremities are approached. In order to secure a greater nicety of adjustment of one of said shoes 302 may be made slightly longer than the other. The portion 301 rests against a washer 338 controlled by a nut 34,0 mounted on the stud 37 and by adjustment of said nut 3&0 the amount of contact between the shoes 302, 302 may be varied and thus the amount of cross section area available for the passage of magnetic flux through pole-piece 42 may readily be varied at will.

It will thus be seen that I have devised a marginal relay in which adjustments required in the maintenance of a telephone exchange may be easily, quickly and efficiently made. Furthermore, the adjustments required during the manufacturing operations can be readily and accurately made. Such adjustments can be made entirely independent of the springs as well as of the contact pressure.

A mass of paramagnetic material is understood to be saturated when it is magnetized to that point beyond which a relatively great increase in magnetizing force is required to produce an appreciable increase in magnetic density. In Hobarts Dictionary of Electrical Engineering, volume 11, page 461, there is shown the point K in the figure, and it is approximately this point that is flowing in the circuit of meant by the term saturation point in the foregoing description.

In the drawings the horizontal distances between armatures 30 and 32 and the polepiece are shown somewhat exaggerated. It is miderstood, however, that suitable air gaps in accordance with the attractive strength of the relay may be provided.

It will be readily understood that the in vention may be practiced in a variety of forms and the scope thereof is not to be determined by the present disclosure, reference being had to the appended claims for that purpose.

Having thus described the invention, what is claimed is:

1. In a relay, the combination with a straight core, an element mounted on said core and forming an extension thereof, a magnet for energizing said core, an armature of relatively small effective cross section area forming one return path for magnetic lines of force produced in said core by energization of the magnet, a second armature having relatively greater effective cross section area formii'ig a second return path in shunt with said first named return path, and a tapered member mounted on said element for ariably limiting the effectiveness of one of said return paths.

2. In a relay, the combination with a straight core, an element mounted on said core and forming an extension thereof, a magnet for energizing said core, an armature of relatively small effective cross section area forming one return path for magnetic lines of force produced in said core by energization of the magnet, a second armature having relatively greater effective cross section area forming a second return path in shunt with said first named return path, and a tapered member mounted on said element for variably limiting the effectiveness of the first of said return paths.

In a relay, the combination with a straight core, a magnet mounted thereon for energizing the core, a resilient member mounted on the core and forming an extension thereof, a tapered member having one end mounted on said resilient member and adjustable to vary the effective cross section area of at least a portion of the magnetic circuit of the relay, and an armature forming the magnetic return for the relay. 7

In an electromagnetic relay, a pole piece, an element formed of non-magnetic material and forming an extension of the pole piece, a pair of armatures forming branch magnetic circuit elements in shunt with each other, each of said armatures having a pivoted end and a free on d, the free ends of said armatures being normally spaced from and oppositely disposed to said pole piece, a wedge shaped member, mounted on said element included in the branch magnetic circuit of one of said lOU posed to said pole piece, a tapered member mounted onsaid element included in the branch magnetic circuit of one of said armatnres, and means for adjustably positioning said tapered member.

In testimonywhereof, I have hereunto set my hand and afiixed my seal this 19 day of March, 1921.

GEORGE ALBEN E. LUNDELL. 

